Browsing by Author "Matiru, Viviene"

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    Cultural Characterization of Fungi Isolated From Oil Contaminated Soils
    (IISTE, 2015) Catherine, Catherine; Budambula, Nancy; Okoth, Sheila; Kagali, Robert; Matiru, Viviene
    Application of Fungi for effective removal of hydrocarbon contamination from soil is being considered as the better option when it comes to biodegradation. Other method like physical and chemical bioremediation leads to production of toxic compounds and these methods are not cost effective. In the present study, soil samples from four different oil contaminated soils were assessed for any recovery of fungi present. Cultural characterization was used as preliminary identification using keys. Initial isolation from the oil contaminated soil was done using potato dextrose agar. Colonies were observed and characterized morphologically. The isolates were grown at varied temperatures and pH. Eight fungal isolates were recovered from polluted soils namely, Trichoderma viride, Trichoderma spirale, Neosartorya pseudofischeri, Neosartorya aureola, Aspergillus flavus, Aspergillus terreus, Penicillium griseofulvum and Trichoderma longibrachiatum. The optimum growth temperature range for the eight fungi was 30oC and 40oC. There was no growth at 50oC for all isolates except some slight growth by Aspergillus flavus. Optimum growth at pH 7 and pH 9 and poor growth at pH 5 was noted. This study will contribute to the database on locally available fungal diversity and their ecology.
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    Potential of indigenous bradyrhizobia versus commercial inoculants to improve cowpea (Vigna unguiculata L. walp.) and green gram (Vigna radiata L. wilczek.) yields in Kenya
    (2012) Mathu, Samuel; Herrmann, Laetitia; Pypers, Pieter; Matiru, Viviene; Mwirichia, Romano K.; Lesueur, Didier
    Limited information is available on reduced cowpea (Vigna unguiculata L. Walp.) and green gram (Vigna radiata L.Wilczek.) yields in Kenya. Declining soil fertility and absence or presence of ineffective indigenous rhizobia in soils are assumptions that have been formulated but still require to be demonstrated. In this study, soils were collected from legume growing areas of Western (Bungoma), Nyanza (Bondo), Eastern (Isiolo), Central (Meru) and Coast (Kilifi) provinces in Kenya to assess indigenous rhizobia in soils nodulating cowpea and green gram under greenhouse conditions. Our results showed that highest nodule fresh weights of 4.63 and 3.32 g plant_1 for cowpea and green gram were observed in one soil from Isiolo and another from Kilifi, respectively, suggesting the presence of significant infective indigenous strains in both soils. On the other hand, the lowest nodule fresh weights of 2.17 and 0.72 g plant_1 were observed in one soil from Bungoma for cowpea and green gram, respectively. Symbiotic nitrogen (N) fixation by cowpea and green gram was highest in Kilifi soil with values of 98% and 97%, respectively. A second greenhouse experiment was undertaken to evaluate the performance of commercial rhizobial inoculants with both legumes in Chonyi soil (also from Coast province) containing significant indigenous rhizobia [>13.5_103 Colony Forming Units (CFU) g_1]. Rhizobial inoculation did not significantly (P < 0.05) affect nodulation, biomass yield and shoot N content in cowpea and green gram compared with controls. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the 16S-23S rDNA intergenic spacer (IGS) region analysis of nodules revealed six groups of which only IGS Group IV corresponded with those from commercial inoculants applied, indicating a lower competitiveness of inoculated strains. In cowpea, IGS III was dominant in nodules of plants inoculated with Biofix and Rizoliq commercial inoculants, and the uninoculated control treatment (63.2, 60 and 52.9%, respectively). Similarly, in green gram, IGS Group III was dominant in nodules of plants inoculated with Biofix 704 and Rizoliq commercial inoculants, and the uninoculated control treatment (75, 73.7 and 61.1%, respectively). Our results suggest that the systematic inoculation of both legumes with current available commercial inoculants to improve biomass yields is not necessary in these regions of Kenya. Also, according to our study, it would make sense to promote the utilization of indigenous strains performing well with both legumes.